package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.*;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;
import static java.util.concurrent.Executors.newFixedThreadPool;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 沉梦听雨
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    /**
     * @Resource注解是Java自身的注解,@Autowired注解是Spring的注解.
     * Resource注解用于根据名称来注入Bean，它可以通过name属性指定Bean的名称。
     * Autowired注解用于根据类型来注入Bean，它会自动寻找与指定类型匹配的Bean并注入。
     * 总的来说，Resource注解更适合通过名称来注入，Autowired注解更适合通过类型来注入。
     */
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryBuId(Long id) {
        // 1.设置空值解决缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        // 2.互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        // 3.逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);

        // 7.返回
        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = newFixedThreadPool(10);
    //逻辑过期解决缓存击穿
    public Shop queryWithLogicalExpire(Long id) {
        // 获取key："cache:shop:" + id
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断 命中的是否是空值
        if (StrUtil.isBlank(shopJson)) {
            // 3.为空，直接返回错误信息
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(),Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断缓存是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            //5.1.未过期，直接返回店铺信息
            return shop;
        }
        //5.2.已过期，需要缓存重建
        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2.判断是否获取锁成功
        if(isLock) {
            //6.3.成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit( ()->{
                try {
                    //重建缓存 20秒
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        //6.4.返回过期的商铺信息
        return shop;

    }

    //互斥锁解决缓存击穿
    public Shop queryWithMutex(Long id){
        // 获取key："cache:shop:" + id
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在缓存
        if (StrUtil.isNotBlank(shopJson)) {
            // 3.存在缓存，直接返回（将redis中的JSON数据转换成对象）
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        // 判断命中的是否是空值（空字符串）。此时值可能是 空字符串，null
        if (shopJson != null) {
            return null;
        }
        // 4.实现缓存重构
        String lockkey = "lock:shop:" + id;
        Shop shop = null;
        try {
            // 4.1获取互斥锁
            boolean isLock = tryLock(lockkey);
            // 4.2判断是否获取成功
            if(!isLock) {
                // 4.3失败，则休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            // 4.4成功，根据id查询数据库
            shop = getById(id);
            // 模拟重建的延时
            Thread.sleep(200);
            // 5.不存在,返回错误
            if(shop == null) {
                //设置 空字符串（空值），预防缓存穿透
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            // 6.数据库存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放互斥锁
            unLock(lockkey);
        }
        // 8.返回
        return shop;
    }

    // 设置空值解决缓存穿透
    public Shop queryWithPassThrough(Long id) {
        // 获取key："cache:shop:" + id
        String key = CACHE_SHOP_KEY + id;
        // 1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在缓存
        if (StrUtil.isNotBlank(shopJson)) {
            // 3.存在缓存，直接返回（将redis中的JSON数据转换成对象）
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        // 判断命中的是否是空值（空字符串）。此时值可能是 空字符串，null
        if (shopJson != null) {
            return null;
        }
        // 4.不存在缓存，根据id查询数据库
        Shop shop = getById(id);
        // 5.数据库不存在，返回错误
        if(shop == null) {
            //设置 空字符串（空值），预防缓存穿透
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        // 6.数据库存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 7.返回
        return shop;

    }

    public void saveShop2Redis(Long id, long expireSeconds) throws InterruptedException {
        // 1.查询店铺数据
        Shop shop = getById(id);
        //休眠200毫秒
        Thread.sleep(200);
        // 2.封装逻辑过期时间，含数据
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2.更新缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        // GEORADIUS key longitude latitude radius m|km|ft|mi [WITHCOORD] [WITHDIST] [WITHHASH] [COUNT count] [ASC|DESC] [STORE key] [STOREDIST key]
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .radius(
                        key,
                        new Circle(new Point(x, y), new Distance(5000)),
                        RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs().includeDistance().limit(end)
                );
        // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE      --Redis6.2以后新功能
        /*GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );*/
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());

        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }

    // 上锁
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    // 删锁
    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }

}
